Conductive Cable System for Suspending A Low Voltage Luminaire Assembly

ABSTRACT

A low voltage cable for providing low voltage power to an electrically-powered assembly, such as a luminaire fixture, and for attaching the luminaire fixture to the cable and to structure using a cable gripping device in such a way that the assembly can be adjusted. is disclosed. The cable comprises a conductive strand composed of a first metallic material, and a plurality of strength strands wound around the conductive strand, where the plurality of strength strands is of a second metallic material. The first metallic material is substantially more conductive than the second metallic material, and the second metallic material has substantially greater tensile strength than the first metallic material. This allows the cable to conduct a low voltage feed across the conductive strand, and allows the strength strands cable to mostly support the tension load particularly of a hanging luminaire fixture as well as resisting lateral compressive forces from a cable gripping device.

TECHNICAL FIELD

The presently disclosed subject matter relates to low voltage suspensionsystem particularly for, but not limited to, luminaire assemblies. Moreparticularly, the subject matter relates to a suspension system thatincludes an uninsulated wire construct for supporting the assembly andfor providing the assembly with low voltage power, as well as adjustablecable grippers and non-adjustable cable couplers to attached the wireconstruct(s) to both supporting structure and luminaire respectively insuch a way that the luminaire may be easily adjusted to the desiredheight.

BACKGROUND

Many electrically-powered assemblies and devices, such as luminaireassemblies, are hung from ceilings or other supporting structures. Inorder for a luminaire assembly to be hung, the weight of the luminaireassembly must be supported from the supporting structure. In addition,in order to provide light, the luminaire assembly must be provided withpower.

Many kinds of supports have been developed to hang luminaire assembliesand to provide them with power. One form of support is an electricalcable configured to provide both power and support to the luminaireassembly. However, electrical cables composed of highly electricalmetallic conductors can only suspend luminaires up to approximately 5pounds. When an electrical cable needs to support more than 5 pounds, aseparate suspension or support cable is required, and the electricalcable will require an insulating jacket of a non-metallic material suchas a polymer or elastomer.

The use of non-metallic insulators with metallic conductive cables cancause a number of problems with the use of adjustable cable grippers.Specifically, adjustable cable grippers need to come into direct contactwith the metallic cable to be effective. When a cable gripper is used ona non-metallically insulated cable it will slip and tear the insulation,eventually lodging against the metal itself and defeating the purpose ofthe insulation.

The use of mixed strands of metallic cable for both supporting lightassemblies and conducting electricity thereto are known. Severalattempts to meet the goal of adequate support and strength in the cable,while still providing adequate conductivity are shown in the prior art.However, these attempts do not cure the problems with the use ofadjustable grippers.

Several examples from the prior art disclose cables which use acombination of cooper wires and steel wires. Some of those examplesdepict steel wires and copper wires exposed on the outer layer of thecable. U.S. Pat. No. 2,250,907, issued to Edwards, and U.S. Pat. No.3,339,012, issued to Hutchins, depict some of those cables. While copperhas good electrical conductivity, copper also has a low elasticstrength. The presence of the copper on the outer later of the cablemeans that the exterior of the cable lacks the lateral compressionstrength required for the cable to be gripped with adjustable grippers.

Other examples in the prior art depict the steel wires on the outerlayer of a cable, but those cables are not configured to be gripped byadjustable grippers. U.S. Pat. No. 2,396,734, issued to Williams, andU.S. Patent Application Publication No. 2001/0000590, applied for byValadez et al, depict some of those cables.

Other examples in the prior art use alternative metallic materials toprovide both conduction and tensile strength. However, those alternativemetallic materials lack the lateral compressive strength for use withadjustable grippers. U.S. Pat. No. 3,261,908, issued to Roche et al, andU.S. Patent Application Publication No. 2001/0017219, depict some ofthose cables.

Yet other examples in the prior art require non-metallic insulationwhich, as discussed above, is destroyed which gripped by an adjustablegripper. U.S. Pat. No. 7,462,781, and U.S. Patent ApplicationPublication No. 2005/0109530, applied for by Maeda, depict some of thosecables.

While all of these prior art cables use metallic strands to providetensile strength for the cable, the prior art cables fail to disclose acable with sufficient lateral compression strength to be gripped with anadjustable gripper, configured to be gripped by an adjustable gripper,and without the use of a polymer or elastomer insulation. The prior artfails to disclose the outer steel strands as providing protection to theinternal conductive strand against the lateral compression forces of anadjustable cable gripping mechanism such as a three-ball compressionsystem.

What is needed in the area of supporting luminaires and other electricalequipment is a conductive cable providing both axial tensile strengthand resistance to lateral compression forces that is needed to support ahanging luminaire assembly or other electrical equipment using anadjustable cable gripper.

SUMMARY

The present disclosure relates to a low voltage cable for providing lowvoltage power to an electrically powered assembly, particularly aluminaire fixture or illuminated sign, and for supporting the luminairefixture while hanging in such a way that the height may be easilyadjusted during installation The cable comprises a conductive strandcomposed of a first metallic material, and a plurality of strengthstrands wound around the conductive strand, the plurality of strengthstrands composed of a second metallic material. The first metallicmaterial is substantially more conductive than the second metallicmaterial, and the second metallic material has substantially greatertensile strength than the first metallic material. This allows the cableto conduct a low voltage feed across the conductive strand, and allowsthe cable to support the tension load of a hanging luminaire fixture.Although it is preferable to use the cable system to suspend a luminaireassembly, other electronically-powered equipment that could be poweredwith low voltage electricity, such as other lights, sensors,microphones, decorations, and the like, can be used with the presentsuspension system.

The present disclosure also relates to a system for an adjustablehanging, particularly a luminaire assembly. The system includes aluminaire fixture assembly or illuminated sign with two or more fixturemounts attached to the luminaire fixture assembly. The system alsoincludes two or more ceiling mounts attached to a ceiling and one ormore power sources remote from the luminaire assembly. Two or more ofthe low voltage cables described above each connect one of the ceilingmounts to one of the fixture mounts in order to hang the luminairefixture assembly from the ceiling. In addition, the remote power sourceprovides power to a light source inside of the luminaire fixtureassembly via low voltage electric feeds directed via the conductivestrands of the low voltage cables.

For low voltage electrical systems, a minimum 24AWG conductive cable isrequired. For the conductive portion of the cable, in this case copper,to be an equivalent 24AWG size the outer diameter of the cable wouldthen be 1.8 mm. The theoretical strength of the 1.8 mm cable alone is645 pounds. No other conductive cable of this size would be able tosupport this weight.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing Summary, as well as the following Detailed Description, isbetter understood when read in conjunction with the appended drawings.In order to illustrate the present disclosure, various aspects of thedisclosure are shown. However, the disclosure is not limited to thespecific aspects shown. The following figures are included:

FIG. 1 illustrates a cross section of an example suspension cable;

FIGS. 2A and 2B illustrate a side view of two example suspension cables,with one of the two examples showing a swaged sleeve;

FIG. 3 illustrates an example hanging luminaire assembly;

FIGS. 4A and 4B illustrate an example ceiling-mounted non-adjustablecable coupler.

FIGS. 5A and 5B illustrate an example ceiling-mounted adjustable cablegripper.

FIGS. 6A and 6B illustrate an example fixture-mounted non-adjustablecable coupler;

FIGS. 7A and 7B illustrate a first example fixture-mounted adjustablecable gripper

FIGS. 8A and 8B illustrate a second example fixture mounted adjustablecable gripper.

FIGS. 9A and 9B illustrate an example 3-ball adjustable cable gripper.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1 depicts a cross section of an example low voltage suspensioncable 101. The cable comprises a conductive strand 102 and strengthstrands 103. The strength strands 103 are wound around conductive strand102 so that conductive strand 102 is covered. The conductive strand 102is capable of conducting low voltage electric power. The strengthstrands 103 are substantially less conductive than the conductive strand102, and have sufficient tensile strength to support a hanging luminaireassembly from the ceiling. Sufficient tensile strength may be on theorder of 500 lbs gross break weight when used with an adjustable cablegripper and a 3/32″ diameter cable. The strength strands 103 alsoprotect the conductive strand 102 from lateral compression forcesimposed by the adjustable cable gripper. The low voltage suspensioncable 101 can be configured in a number of different embodiments.Furthermore, other electronically-powered equipment that could bepowered with low voltage electricity, such as other lights, sensors,microphones, decorations, and the like, can be used with the presentsuspension system.

In one embodiment of the low voltage suspension cable 101, conductivestrand 102 comprises a plurality of conductive wires 104, and each ofthe plurality of strength strands comprises a plurality of strengthwires 105. The embodiment shown in FIG. 1 depicts conductive strand 102comprising seven conductive wires 104, and depicts strength strands 103each comprising seven individual strength wires 105. The configurationof the seven-wire strand includes a center wire and six wiressurrounding the center wire.

In another embodiment of the low voltage suspension cable 101,conductive strand 102 comprises seven copper wires with a minimum crosssectional equivalent of 24AWG as required for Class 2 systems. Strengthstrands 103 each comprise seven 304 stainless steel wires.

FIG. 2A depicts a length of low voltage suspension cable 101. As shown,strength strands 103 are wound such that conductive strand 102 is notexposed. The terminals 201 of low voltage suspension cable 101 can beelectro-cut, soldered, or finished in any similar manner or unfinished.The length of the low voltage suspension cable 101 can vary depending onthe application in which the cable is used.

FIG. 2B depicts a length of low voltage suspension cable 101 whichincludes a swaged sleeve 202. Swaged sleeve 202 can be used as part of aconnector system for connecting the cable to a ceiling or to a luminaireassembly.

FIG. 3 depicts an example luminaire assembly system. This systemincludes a remote power source 301. The remote power source 301 isconnected to two electrical leads 302. Electrical leads 302 are directedto ceiling mounts 303. Ceiling mounts 303 securely attach low voltagesuspension cables 101 to ceiling or other structure 304 (not shown). Inceiling mounts 303, electrical leads 302 are connected to the conductivecore 102 of low voltage suspension cables 101. Fixture mounts 305securely attach low voltage suspension cables 101 to luminaire assembly306. Low voltage suspension cables 101 are connected to ceiling mounts303 and fixture mounts 305 in such a way as to properly support hangingluminaire assembly 306. Electrical leads 307 are connected to theconductive core 102 of low voltage suspension cables 101. Electricalleads 307 are directed inside of luminaire assembly 306 to a lightingelement (not shown) of luminaire assembly 306. As depicted in FIG. 3,low voltage suspension cables 101 can support the weight of hangingluminaire assembly 306 and provide low voltage power to luminaireassembly 306.

The remote power source 301 may be any type of low voltage power source.The remote power source may provide direct current feeds via each of thelow voltage suspension cables 101, where one or more of the cablesprovides a positive feed and the other cables provide a negative feed.In one embodiment, the remote power source provides a positive 24-voltdirect or alternating current feed on one of the cables, and a negative24-volt direct or alternating current feed on the other cable. Theremote power source may be any other type of device that has anelectrical power output, such as a transformer which can transform ahigh voltage alternating current source into a low voltage alternatingcurrent output. Those skilled in the art will recognize many other typesof remote power source that would be suitable for these purposes.

The light source may be any type of light source which requires a lowvoltage input. As the economic and environmental costs associated withpower generation increase, light sources have been developed which havelow power requirements. These low power light sources include LEDlights, compact fluorescent bulbs, and other similar sources. Becausethese light sources do not require as much electrical energy, they canbe powered by a low voltage power source via low voltage suspensioncables.

FIGS. 4A and 4B depict an example ceiling-mounted non-adjustable cablecoupler 401, in both assembled and exploded views, respectively. Ceilingmount 401 requires a low voltage suspension cable 101 with a swagedsleeve 202. When low voltage suspension cable 101 is inserted throughnon-adjustable cable coupler 403, swaged sleeve 202 sits inside ofnon-adjustable cable coupler 403. Insulating sleeve 409 is inserted ontocable 101 above swaged sleeve 202. Non-adjustable cable coupler 403 isinserted through insulating bushing 404 and bracket bar 405 such thatthe external threads on the body of non-adjustable cable coupler 403extend below bracket bar 405. Bracket bar 405 is fixed to junction box402 by screws 406. The portion of non-adjustable cable coupler 403 whichextends below bracket 405 is passed through the ceiling (not shown) andthrough ceiling canopy 407. Coupler cap 408 has internal threads whichengage the external threads of non-adjustable cable coupler 403 tosecure the ceiling canopy 407 to the ceiling or other structure.

FIGS. 5A and 5B depict an example ceiling mounted adjustable cablegripper 501, in both assembled and exploded views, respectively. Ceilingmount 501 can utilize a low voltage suspension cable 101 without aswaged sleeve 202. Adjustable cable gripper 503 contains an internal3-ball compression system which grips low voltage suspension cable 101and locks it in place. With low voltage suspension cable 101 locked intoadjustable cable gripper 503, the remaining portions of ceiling mount501 are similar to those of ceiling mount 401. Adjustable cable gripper503 in inserted through insulating bushing 504 and bracket bar 505.Bracket bar 505 is secured to junction box 502 using screws 506. Theportion of adjustable cable gripper 503 which extends below bracket 505is passed through the ceiling (not shown) and through ceiling canopy507. The internal threads of coupler cap 508 engage the external threadsof adjustable cable gripper 503 to secure the ceiling canopy 507 to theceiling or other structure. Insulating sleeve 509 is inserted onto cable101 above adjustable cable gripper 503

The components of first ceiling mount 401 and second ceiling mount 501can be composed of a variety of materials. In one embodiment,non-adjustable cable coupler 403, adjustable cable gripper 503, andcoupler caps 408 and 508 are composed of nickel plated brass; bracketsbars 405 and 505 are composed of zinc plated steel; and, insulatingbushings 404 and 504 and ceiling canopies 407 and 507 are composed ofnylon 6/6. Insulating sleeves 409 and 509 are composed of PVC. Those ofordinary skill in the art will recognize that a number of othermaterials can be readily used as substitutes for those described above.

FIGS. 6A and 6B depict an example non-adjustable fixture mount 601, inboth assembled and exploded views, respectively. First ceiling mount 601requires a low voltage suspension cable 101 with a swaged sleeve 202.When low voltage suspension cable 101 is inserted through cable coupler606, swaged sleeve 202 sits inside of cable coupler 606. Insulatingsleeve 607 is inserted onto cable 101 below swaged sleeve 202. Cablecoupler 606 is inserted through insulating bushing 605, through the topof luminaire assembly 604, and through insulating bushing 603. Cablecoupler 606 is secured to fixture assembly 604 with nut 602, where theinternal threads of nut 602 engage the external threads of cable coupler606.

FIGS. 7A and 7B depict an example first adjustable fixture mount 701, inboth assembled and exploded views, respectively. First adjustablefixture mount 701 can utilize a low voltage suspension cable 101 withouta swaged sleeve 202. Adjustable cable gripper 706 contains an internal3-ball compression system which grips low voltage suspension cable 101and locks it in place. Low voltage suspension cable 101 is insertedthrough insulating bushing 705, through luminaire assembly housing 704,and through insulating bushing 703 Adjustable cable gripper 706 issecured to fixture assembly housing 704 with nut 702, where the internalthreads of nut 702 engage the external threads of cable gripper 706.Insulating sleeve 707 is inserted onto cable 101 below adjustable cablegripper 706.

FIGS. 8A and 8B depict an example second adjustable fixture mount 801,in both assembled and exploded views, respectively. Second adjustablefixture mount 801 can utilize a low voltage suspension cable 101 withouta swaged sleeve 202. Adjustable cable gripper 806 grips low voltagesuspension cable 101 securely and locks it in place. Adjustable cablegripper 806 differs from adjustable cable gripper 706 in external designonly: Adjustable cable gripper 706 is inserted into luminaire assemblyhousing 704 from below the housing wall and adjustable cable gripper 806is inserted into luminaire assembly housing 804 from above the housingwall. Low voltage suspension cable 101 is inserted through insulatingbushing 803, through luminaire assembly housing 804, and throughinsulating bushing 805. Cable gripper 806 is secured to fixture assemblyhousing 804 with nut 802, where the internal threads of nut 802 engagethe external threads of cable gripper 806. Insulating sleeve 807 isinserted onto cable 101 below cable gripper 806. Those of ordinary skillin the art will recognize that a number of other adjustable cablegripper designs can be readily used as substitutes for those describedabove.

The components of non-adjustable fixture mount 601, the first adjustablefixture mount 701, and the second adjustable fixture mount 801 can becomposed of a variety of materials. In one embodiment, non-adjustablecable couplers and adjustable cable grippers 606, 706, and 806 arecomposed of nickel plated brass; and bushings 603, 605, 703, 705, 803,and 805 are composed of nylon 6/6; insulating sleeves 607,707, and 807are composed of PVC Those of ordinary skill in the art will recognizethat a number of other materials can be readily used as substitutes forthose described above.

Referring back to the example luminaire assembly system depicted in FIG.3, the ceiling mounts 303 and the fixture mounts 305 can be any of theabove example mounts or similar mounts. Among the possible pairings ofceiling mounts 303 with fixture mounts 305, and the associated lowvoltage cable required, include those described in Table 1.

TABLE 1 Possible pairings of low ceiling and fixture mounts CeilingMount Fixture Mount Low Voltage Cable First ceiling mount 401 Firstfixture mount 601 Swaged sleeve 202 at both ceiling and fixture endFirst ceiling mount 401 Second fixture mount 701 Swaged sleeve 202 atceiling end First ceiling mount 401 Third fixture mount 801 Swagedsleeve 202 at ceiling end Second ceiling mount 501 First fixture mount601 Swaged sleeve 202 at fixture end Second ceiling mount 501 Secondfixture mount 701 No swaged sleeve 202 required Second ceiling mount 501Third fixture mount 801 No swaged sleeve 202 required

FIGS. 9A and 9B illustrate an example 3-ball adjustable cable gripper901. In the embodiment shown in FIG. 9A, the adjustable cable gripper901 has a stop flange 902 and a threaded body 903. When installed, thethreaded body 903 is inserted in a through hole of a ceiling, a fixture,or other structure (not shown) until the stop flange 902 comes intocontact with the structure. FIG. 9A depicts a sectional view of threadedbody 903 with the top half removed. An internal conical cylinder 904 isinside of threaded body 903, and is also depicted in a sectional viewwith the top half removed. The threaded body 903 surrounds the internalconical cylinder 904 that, in turn, contains three balls 905. If adownward force is exerted on the low voltage suspension cable 101, thecable will transmit the downward force on the internal conical cylinder904. This downward force on the internal conical cylinder 904 causes theballs 905 to be compressed between the threaded body 903 and the lowvoltage suspension cable 101. This compression of the balls 905 causes alateral force to be applied from each ball 905 toward the axis of thelow voltage suspension cable 101. These lateral forces prevents the lowvoltage suspension cable 101 from moving downward, despite the forcepulling the low voltage suspension cable 101 downward.

FIG. 9B depicts a sectional view looking down the axis of the lowvoltage suspension cable 101. As depicted, low voltage suspension cable101 includes conductive strand 102 and strength strands 103. Alsodepicted are sectional views of the threaded body 903, the internalconical cylinder 904, and the three balls 905. As can be seen, the ballscome into direct contact with the outer edge of the low voltagesuspension cable 101. If a polymer or elastomer insulation jacket wereused on the outside of low voltage suspension cable 101, the lateralforces applied by the balls would permanently deform the insulation(e.g., tearing or stretching the insulation). Further, a polymer orelastomer insulation jacket does not have the tensile strength requiredto support a hanging fixture.

The foregoing description has set forth various embodiments of thesystem and components via the use of diagrams and examples. While thepresent disclosure has been described in connection with the preferredembodiments of the various figures, it is to be understood that othersimilar embodiments may be used or modifications and additions may bemade to the described embodiment for performing the same function of thepresent disclosure without deviating there from. Therefore, the presentdisclosure should not be limited to any single embodiment, but ratherconstrued in breadth and scope in accordance with the appended claims.Additional features of this disclosure are set forth in the followingclaims.

1. A cable for conducting low voltage electrical power and for supporting tension loads and resisting lateral compression forces, the cable comprising: a conductive strand composed of a first metallic material; and a plurality of strength strands wound around the conductive strand, the plurality of strength strands composed of a second metallic material; wherein the first metallic material is substantially more conductive than the second metallic material, and wherein the conductive strand has sufficient conductivity to carry low voltage electrical power; wherein the second metallic material has substantially a greater tensile strength than the first metallic material such that the plurality of strength support tension loads and resist lateral compression forces.
 2. The cable of claim 1, further comprising a swaged sleeve fixed around the plurality of strength strands near one end of the cable.
 3. The cable of claim 1, wherein one end of the cable is an electro-cut cable end, a soldered cable end, or an unfinished cable end.
 4. The cable of claim 1, wherein the first metallic material is one of the following: copper, a copper alloy, or non-cuprous, highly conductive material.
 5. The cable of claim 1, wherein the second metallic material is one of the following: steel, stainless steel, or another high tensile strength, high lateral compressive strength material.
 6. The cable of claim 1, wherein the conductive strand comprises a plurality of conductive wires, and wherein at least one of the plurality of strength strands comprises a plurality of strength wires.
 7. The cable of claim 6, wherein the conductive strand consists of seven copper wires, and wherein each of the plurality of strength strands consists of seven stainless steel wires.
 8. A hanging electrically-powered assembly system, comprising: an electrically-powered assembly; two fixture mounts attached to the electrically-powered assembly; two structure mounts attached to a structure; a power source remote from the electrically-powered assembly; two conductive cables each connected to one structure mount and to one fixture mount without the use of insulation between the structure mount and the fixture mount, wherein each conductive cable comprises: a conductive strand composed of a first metallic material, the conductive strand connecting the power source to the electrically-powered assembly, and a plurality of strength strands wound around the conductive strand, the plurality of strength strands composed of a second metallic material.
 9. The system of claim 8, wherein the hanging electrically-powered assembly is a luminaire fixture assembly comprising a light source.
 10. The system of claim 9, wherein the light source comprises at least one low voltage, low power light.
 11. The system of claim 8, wherein the first conductive cable comprises a swaged sleeve near one end of the first conductive cable.
 12. The system of claim 11, wherein the first structure mount comprises a non-adjustable cable coupler, and wherein the swaged sleeve of the first conductive cable sits in the non-adjustable cable coupler of one structure mount.
 13. The system of claim 12, wherein the first fixture mount comprises an adjustable cable gripper, and wherein the end of the first cable further from the swaged sleeve is attached to the adjustable cable gripper of one fixture mount.
 14. The system of claim 11, wherein the first fixture mount comprises a non-adjustable cable coupler, and wherein the swaged sleeve of the first conductive cable sits in cable coupler of one fixture mount.
 15. The system of claim 14, wherein the first structure mount comprises an adjustable cable gripper, and wherein the end of the first cable further from the swaged sleeve is attached to the cable gripper of one structure mount.
 16. The system of claim 8, wherein each remote power source is configured to provide a positive 30-volt or less direct current feed via a first conductive cable, and to provide a negative 30-volt or less direct current feed via a second conductive cable.
 17. The system of claim 8, wherein the first metallic material is one of the following: copper, a copper alloy or a non-cuprous, highly conductive material; and wherein the second metallic material is one of the following: steel, stainless steel or other high tensile strength, high lateral compressive strength material.
 18. The system of claim 8, wherein the conductive strand of each conductive cable comprises a plurality of conductive wires.
 19. The system of claim 8, wherein at least one of the plurality of strength strands of each conductive cable comprises a plurality of strength wires.
 20. A hanging electrically-powered assembly system, comprising: means for consuming electricity; two means for mounting to a fixture attached to the means for consuming electricity; two means for mounting to a structure attached to a structure; means for providing power remote from the means for consuming electricity; two means for hanging each connected to one means for mounting to a fixture and to one means for mounting to a structure without the use of insulation between the means for mounting to a fixture and the means for mounting to a structure, wherein each means for hanging comprises: means for conducting composed of a first metallic material, the means for conducting connecting the means for providing power to the means for consuming electricity, and means for proving tensile strength wound around the means for conducting, the means for providing tensile strength composed of a second metallic material. 